docs: def _getMyFirstDatetimeTo(self):
          """
          The datetime this event first finished, or None if it never did.
          """
          myFirstDt = self._getMyFirstDatetimeFrom()
          if myFirstDt is not None:
              daysDelta = dt.timedelta(days=self.num_days - 1)
              return getAwareDatetime(myFirstDt.date() + daysDelta,
                                      self.time_to,
                                      self.tz, dt.time.max)